The studies included in this project are primarily concerned with the role of lipids in membrane function in red blood cells. In addition to the continuing, previously reported, areas of interest which included the consequences of peroxidation of membrane lipids, the nature of membrane remodeling during hemolysis, and the role of ATP in membrane renewal, new areas of interest have been developed. These include: (1) the role of membrane protein phosphorylation in the maintenance of cell shape; (2) the preparation ofa useful "hybrid" sickle cell model which enables us to study the membrane independent from the hemoglobin; (3) the nature of hemoglobin: water interactions during the sickling process; and, (4) the development of a calorimetric method for directly measuring metabolic events during red cell glycolysis.